Role of Different Leaching Methods to Arrest the Transport of Ni²⁺ in Soil and Soil Amended with Nano Calcium Silicate

Soils are known to retain heavy metals through a number of processes. Human exposure to highly nickel polluted environments has the potential to produce a variety of pathological effects. Some of them are skin allergies, fibrosis of lungs and cancers of the respiratory tracts. In this study four different leaching methods viz. ASTM D3987, Toxicity characteristics leaching procedure (TCLP), extended TCLP, and caged TCLP have been used to study the leaching behavior of Ni²⁺ on red soil and red soil amended with nano calcium silicate (NCS). It was found that as per ASTM D3987, Ni²⁺ with red soil was retained well in the short term and over a long term period the metal ion was released back. Red soil was amended with NCS and it was found that over a period of time the retention was satisfactory which proved that NCS was responsible for encapsulation of Ni²⁺ in its matrix. Extensive leaching tests were further performed; it was found that as per TCLP, extended TCLP and caged TCLP tests the retention of Ni²⁺ with amended soil was 88%, 90% and 94% better than soil respectively Hence it can be concluded that NCS amended soil is a prospective material to attenuate Ni²⁺ taking into consideration the long term effect of heavy metals on soils.